Heroic Bindings

Mageknights are commoners with advanced combat magic controlled by the Cult of Yan through the Heroic Bindings, also colloquially known as the Black Curse. It's a magecraft curse that would cause pain to any Mageknight who doesn't undergo a ritual called the Lifting with a certified Cult of Yan cleric to extend the endpoint of the curse every 50 days, if they pass the deadline their ability to use magecraft is severed permanently. The Black Curse is so called because on receiving the certification, the Mageknight sees a vision of a dark mist enveloping them, though there are no tangible effects after the ceremony.

A ritual called a Pre-lifting can extend that 50 days to 100 days. And this can be done one more time to 150 days max. The Pre-lifting can be done by a loyalist priest without an official Yan cleric.